How can you identify a transformer in a TPC schematic?

In TPC schematics, a transformer is represented by two coils that symbolize the primary and secondary windings. This visual representation distinctly indicates the function of the transformer, which is to transfer electrical energy between these two windings through electromagnetic induction. The primary winding receives power from the source, while the secondary winding delivers power to the load. This dual-coil symbol effectively communicates the operational principle of the transformer, showing how energy is transferred between the circuits.

The other symbols mentioned in the options do not accurately represent a transformer. For example, a square labeled with input and output may suggest a box-like component but lacks the details necessary to convey the induction principle specific to transformers. Similarly, a zigzag line typically represents resistance, and a triangle with central dots is associated with other components in electrical diagrams, not transformers. Therefore, the option featuring the two coils is the clear and correct choice for identifying a transformer in a TPC schematic.